The invention relates generally to an active matrix panel and more particularly to a high density active matrix panel formed with thin film transistors, for driving a liquid crystal display (LCD).
A conventional active matrix liquid crystal display panel including a matrix of liquid crystal picture elements formed with thin film transistors (TFT's) on a transparent substrate is described in Morozumi et al., "Black and White and Color Liquid Crystal Video Displays Addressed by Polysilicon TFTs", SID-83 Digest, pp. 156-57 and is shown in FIG. 19. A monocrystalline silicon MOS integrated gate line driver circuit 4' for driving a plurality of gate lines 4a' and a source line driver circuit 4 for driving a plurality of orthoganol source lines 4a are formed on a flexible substrate 3. An active matrix panel 1 includes a matrix of liquid crystal picture elements at the cross-over of respective gate lines 4a' and source lines 4a and a plurality of electrical connection pads 5. Driving circuits 4 and 4' are electrically coupled to panel 1 at pads 5. Both flexible substrate 3 and panel 1 are mounted on a substrate 6 and integrated driver circuits 4 and 4' are electrically coupled to other circuitry (not shown).
Such conventional active matrix panels can provide viewable displays, but they can have the following disadvantages.
1. Inadequate resolution.
Flexible substrate 3 and source lines 4a and gates lines 4a' of active matrix panel 1 are electrically coupled at pads 5. Accordingly, the picture elements cannot be sufficiently densely spaced because of the space occupied by pads 5. This interferes with mass production of active matrix panels having a picture element pitch of 100 .mu.m or less and prevents high resolution.
2. Inadequate display device miniaturization.
Driver integrated circuits 4 and 4' are located outside of panel 1 on substrate 6. Accordingly, active matrix panel 1 occupies only about 1/4 or 1/5 of the surface area of substrate 6. Consequently, display devices including conventionally formed active matrix panels are undesirably larger than the picture element matrix portion of the entire panel. This makes it inconvenient to include conventional active matrix panels when miniaturization is needed, such as for a micro-monitor which can be used as an electric view finder for a video camera.
3. High manufacturing costs
Manufacturing a conventional display including an active matrix panel requires many connections as follows. Active matrix panel 1 is connected to flexible substrate 3; driver integrated circuit 4 is connected to flexible substrate 3; and flexible substrate 3 is mounted on mounting substrate 6. These multiple connection steps increase manufacturing costs.
4. Low reliability.
Because conventional active matrix panels require so many connections, when stress is applied to the panel, these connections can come apart. This affects the reliability of the entire display and increases costs because extra measures must be undertaken to compensate for the possibility of disconnections.
Accordingly, it is desireable to develop an improved active matrix panel which does not have the shortcomings of conventional active matrix panels.